JPH06249109A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To improve atomization characteristic by forming a plurality of intake ports on every cylinder under a lean combustion condition, and arranging a plurality of injectors on the intake ports while their injection ports being opposed to an ignition plug. CONSTITUTION:Two intake ports 12a, 12b are formed on every cylinder, while a shutter valve 20 is arranged on one intake port 12a each. Injectors 21, 22 are arranged in the vicinity of a combustion chamber 14 with regard to the respective intake ports 12a, 12b. The injectors 21, 22 each has a single injection port 23 which is directed to an ignition plug 13. The injectors 21, 22 are operated for directly injecting fuel into a cylinder from a gap between a shade of an intake valve and openings of the intake ports 12a, 12b for forming double streams. Two fuel streams are directly and opposingly injected to each other inside the cylinder under an intake process. The atomized fuel streams are struck against each other around the center of the combustion chamber in the vicinity of the ignition plug, and then air-fuel mixture which is capable of being rich forms a layer. The atomized fuel is further atomized by the help of assist air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an engine, and more particularly to a fuel injection device for an engine that performs lean burn.

[0002]

2. Description of the Related Art Conventionally, there has been developed a fuel injection system for an engine which improves fuel efficiency by performing lean combustion. The lean combustion is performed by utilizing the in-cylinder flow of swirl, tumble, squish, etc. to make the air-fuel mixture uniform and achieve rapid and stable combustion.

When lean combustion is performed by utilizing such in-cylinder flow, the effect saturates when the air-fuel ratio (A / F) is around 22, so the fuel efficiency is improved even if the lean limit is further extended. The reality is that we cannot hope for it.

[0004]

Therefore, in order to extend the lean limit and improve the fuel economy, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 3-61716, an injector is provided in an intake port in the vicinity of a combustion chamber, and fuel is injected by the injector from a gap between an umbrella portion of an intake valve and an intake port opening during an intake stroke. What has been done is proposed.

In the one described in this publication, the fuel is directly injected into the cylinder having a low pressure during the intake stroke when the intake valve is lifted, whereby stratification of the air-fuel mixture is achieved and the air-fuel ratio is 30 to 30. It becomes possible to perform a lean burn of about 40. However, since the one described in this publication has only one fuel injection port of the injector, stratification of the air-fuel mixture is possible by optimally setting the injection angle, the injection direction, and the injection timing. Considering the contact of the spray with the valve, the injection direction, and the atomization, there is room for further improvement.

Therefore, the present invention has been made in order to further improve the conventional device, and provides a fuel injection device for an engine capable of injecting fuel having excellent vaporization and atomization characteristics into a central portion of a combustion chamber. It is an object. Another object of the present invention is to provide a fuel injection device for an engine that prevents fuel from adhering to the wall surface of a cylinder and improves fuel consumption and emission characteristics.

[0007]

In order to achieve the above object, the present invention provides an injector in an intake port in the vicinity of a combustion chamber so that a gap between an umbrella portion of an intake valve and an intake port opening is provided during an intake stroke. In an engine fuel injection device for injecting fuel into a cylinder by the injector, a plurality of intake ports are provided for one cylinder, and at least two or more of these intake ports are arranged in the plurality of intake ports, and each of the injection ports has an ignition plug. And an injector which is directed to.

According to the present invention thus constructed, the sprayed fuel, which is directly opposed to the fuel and injected into the cylinder having a low pressure during the intake stroke, collides in the vicinity of the center of the combustion chamber near the spark plug to cause combustion in the combustion chamber. A rich mixture is formed near the center and stratified. In the present invention, a shutter valve is provided in a part of the plurality of intake ports to form swirl generating means, and two injectors are formed in the injector provided in the intake port that does not have the swirl generating means. One of the injection ports is directed toward the spark plug, and the other of the injection ports is directed toward the outer peripheral portion of the cylinder.

Therefore, compared with the one injection port, the spray is dispersed by the two injections, so that even if the fuel injection amount increases, it does not adhere to the wall surfaces of the umbrella part and the stem part, and the air and the fuel are further injected. Mixing is promoted and vaporization atomization is improved. Further, a swirl flow is formed, and the mixing of air and fuel is improved. The present invention further has an assist air supply means for supplying assist air to the two injection ports of the injector, and the assist air supply device has a flow velocity higher than that of the one injection port to the other injection port. I am trying to supply some assist air.

Therefore, by the assist air supply means,
Since it is assisted, it is effective for atomizing the fuel.
When the air-assisted air-fuel mixture collides, atomization is further promoted, and the penetration, which is the force of the spray, is significantly reduced, so the adhering rate of the air-fuel mixture on the opposing wall surface is also reduced, and fuel consumption and emission characteristics are reduced. It is advantageous for improvement. Further, since the assist air is ejected toward the outer peripheral portion of the cylinder, the formation of the swirl flow is promoted and the adhesion of the air-fuel mixture on the wall surface is prevented from being reduced.

Further, in the present invention, since the intake port is the tumble port, a tumble flow is formed in the cylinder.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram showing an embodiment of an engine fuel injection device of the present invention. In FIG. 1, 1 is an engine body, and this engine body 1 is
It is composed of a cylinder 2 and a cylinder head 3.
The intake air passes through an air cleaner 4, an air flow chamber 6 containing an air flow sensor 5, a throttle valve body 8 containing a throttle valve 7, a surge tank 9, an intake manifold 10, an intake port 12 opened and closed by an intake valve 11, and is ignited. It is supplied to the combustion chamber 14 in which the plug 13 is arranged. The path from the air cleaner 4 to the intake port 12 constitutes an intake passage 15.
The amount of intake air flowing through the intake passage 15 is controlled by an opening / closing operation by the throttle valve 7, while being measured by the air flow sensor 5. On the other hand, the exhaust gas from the combustion chamber 14 is exhausted from the exhaust port 1 opened and closed by the exhaust valve 16.
The gas is discharged to the atmosphere via the exhaust passage 18 connected to 7. Further, an injector 20 is provided in the intake port 12 near the combustion chamber 14.

FIG. 2 is a sectional view showing the vicinity of the injector,
FIG. 3 is a plan view showing the vicinity of the injector. As shown in FIGS. 2 and 3, two intake ports 12a and 12b are formed for one cylinder, and a shutter valve 20 is provided in one of the intake ports 12a.
Injectors 21 and 22 are arranged in the vicinity of the combustion chamber 14 of the intake ports 12a and 12b, respectively. These injectors 21 and 22 have a single injection port 23 (see FIG. 4). Each of these injectors 2
The injection ports 23 of 1 and 22 are formed so as to be oriented in the direction of the spark plug 13, respectively.

These injectors 21 and 22 are designed to inject fuel directly into the cylinder through the gap between the cap portion 11a of the intake valve 11 and the intake port opening 25. Here, a swirl flow is formed by closing the shutter valve 20 provided in the intake port 12a. Further, each of the intake ports 12a and 12b is a tumble port and produces the tumble flow shown by A in FIG.

Further, as shown in FIG. 1, an assist air passage 26 is connected to the injectors 21 and 22 via a timed air control valve 27. The upstream end of the assist air passage 26 opens to the upstream side of the throttle valve 7 in the intake passage 15. Therefore, by opening the timed air control valve 27 during the intake stroke, the negative pressure in the cylinder communicates with the atmosphere on the upstream side of the throttle valve 7, and the differential pressure thereof supplies the assist air into the cylinder. To be done. Further, 30 is a fuel tank from which the injector 2
Fuel is supplied to 1, 22.

FIG. 4 is a sectional view showing the injector.
As shown in this figure, each of the injectors 21 and 22 has a single injection port 23, and this injection port 23 is connected to an air assist passage 26. Next, the operation will be described. First,
As shown in FIG. 5, the shutter valve 20 is closed in the low load / low rotation region (A), and the shutter valve 20 is opened in the high load / high rotation region (B). As described above, in the low load / low speed operation region, the shutter valve 20 is closed in the intake stroke in which the intake valve 11 is opened, so that intake air is supplied into the combustion chamber 14 from only one intake port 12b. As a result, a good swirl flow is formed in the cylinder. Further, the tumble flow shown by A in FIG. 3 is generated by both the intake ports 12a and 12b in the high load / high rotation region (B) and only by the intake port 12b in the low load / low rotation region (A).

Further, at this time, by opening the timed air control valve 27, assist air is supplied from the upstream side of the throttle valve 5 to the injection port 23 of the injector 21, 22 through the assist air passage 26. It With this assist air, the injectors 21, 22
Is spray-assisted at the injection port 23 and is directly injected into the cylinder through the gap between the cap portion 11a of the intake valve 11 and the intake port opening 23.

That is, during the intake stroke, the fuel is directly injected into the cylinder having a low pressure so as to face each other. As a result, the spray collides near the center of the combustion chamber in the vicinity of the spark plug and a rich mixture is produced near the center of the combustion chamber. Can be formed and the mixture is stratified. Further, since the spray is assisted by air, it is effective for atomization. Further, the collision of the air-assisted air-fuel mixture further promotes atomization, and the penetration, which is the force of the spray, is greatly reduced, so the adhering rate of the air-fuel mixture on the opposing wall surface is also reduced, and fuel consumption and emissions are reduced. It is advantageous for improving the characteristics.

Next, another embodiment of the present invention will be described with reference to FIGS. 6 is a plan view showing the vicinity of the injector, and FIG. 7 is a sectional view showing the injector.
As shown in FIGS. 6 and 7, an injector 31 is provided in the intake port 12b that does not have the shutter valve 20, and the injector 31 has two injection ports 32 and 33. As shown in FIG. 6, one of these injection ports 32 is directed to the spark plug 13, and the other injection port 32 is directed to the cylinder outer peripheral portion 28 of the engine 1. Also,
The injection port 32 directed to the spark plug 13 is formed to have a larger diameter than the injection port 33 directed to the cylinder outer peripheral portion 28, and the injection ports 32, 33 are respectively branched in the vicinity of the injector 31 to assist air passage 26. Is connected to the branch passages 26a and 26b. As a result, the flow velocity of the air jetted from the jet port 32 becomes smaller than the flow velocity of the air jetted from the jet port 33, and the flow velocity of the air jetted from the jet port 33 is the same as that of the air jetted from the jet port 32. Greater than the flow velocity.

In the other embodiment of the present invention thus constructed, the basic operation is the same as that of the above embodiment. In this embodiment, the injector 31 having the two injection ports 32 and 33 is provided and operates as follows. Compared with the one injection port, the spray is dispersed by the two injection ports 32 and 33, so that even if the fuel injection amount increases, the wall surface of the umbrella portion 11a and the stem portion 11b is not adhered, and more air is generated. Since the mixing property of the fuel is improved, the vaporization and atomization property is improved.

Further, since the spray having a high flow velocity is ejected toward the outer peripheral portion of the cylinder from the injection port 33 directed to the outer peripheral portion 28 of the cylinder, formation of a swirl flow is promoted and fuel adhesion on the cylinder wall surface is prevented. It is advantageous for fuel economy and emission.

[0022]

As described above, according to the fuel injection system for an engine of the present invention, it is possible to inject fuel with excellent vaporization and atomization characteristics into the center of the combustion chamber and prevent fuel from adhering to the cylinder wall surface. Fuel economy and emission characteristics can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a fuel injection device for an engine of the present invention.

FIG. 2 is a cross-sectional view showing the vicinity of the injector in one embodiment of the present invention.

FIG. 3 is a plan view showing the vicinity of an injector in one embodiment of the present invention.

FIG. 4 is a sectional view showing an injector according to an embodiment of the present invention.

FIG. 5 is a diagram for setting the opening / closing of a shutter valve from the relationship between load and rotation speed.

FIG. 6 is a plan view showing the vicinity of an injector according to another embodiment of the present invention.

FIG. 7 is a sectional view showing an injector of another embodiment of the present invention.

[Explanation of symbols]

 1 Engine Body 2 Cylinder 3 Cylinder Head 10 Intake Manifold 11 Intake Valve 11a Intake Valve Head 11b Intake Valve Stem 12 Intake Port 13 Spark Plug 14 Combustion Chamber 20 Shutter Valve 21 Injector 22 Injector 23 Injector 26 Assist Air Passage 27 Timed air control valve 28 Cylinder outer periphery 33 Injector 31 Injector 32 Injection port 33 Injection port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02B 31/02 J 7541-3G F02M 69/04 P 7825-3G

Claims (4)

[Claims] 1. A fuel injection system for an engine, wherein an injector is provided in an intake port in the vicinity of a combustion chamber, and the injector injects fuel into a cylinder from a gap between an umbrella portion of the intake valve and an opening of the intake port during an intake stroke. A fuel for an engine having a plurality of intake ports provided for one cylinder, and at least two injectors arranged at the plurality of intake ports, each of which has an injection port directed toward a spark plug. Injection device. 2. A shutter valve is provided in a part of the plurality of intake ports to form a swirl generating means, and two injectors are formed in an injector provided in the intake port not having the swirl generating means. The fuel injection device for an engine according to claim 1, wherein one of the injection ports faces the spark plug and the other of the injection ports faces the outer peripheral portion of the cylinder. 3. An assist air supply means for supplying assist air to the two injection ports of the injector, the assist air supply means having a flow velocity higher than that of the one injection port at the other injection port. The fuel injection device for the engine according to claim 2, wherein the assist air is supplied. 4. The fuel injection device for an engine according to claim 1, wherein the intake port is a tumble port.